1. Field of the Invention
The present invention relates to prototypes for production of multi-chip modules capable of carrying several integrated circuit chips in a single multi-layer ceramic package, and, in particular, to a pre-production, prototype multi-chip module adapted for preliminary performance timing and functional tests and method of making the same.
2. Description of Related Art
A multi-chip module (MCM) is a module or package capable of supporting several chips on a single package. Most multichip packages are made of multiple layers of ceramic in which the chips are connected by nets formed by conductors in the ceramic layers or extended through holes (vias) between the layers. MCM's are currently used in applications requiring high performance such as frequencies of 200 MHz or more.
There has been a long felt need for a pre-production, prototype MCM which can be used for timing as well as functional verification. Typically, MCM's are prototyped with circuit board containing single chip modules (SCM). In order to run at near operational speeds, these prototyped circuit boards are typically implemented as printed circuits. Although these prototype boards are more useful than the prior yellow wire boards, the prototyped printed circuit boards have considerably higher design and fabrication expense. Additionally, the electrical path length of signals on the prototype boards may prevent use of the boards as means of verifying timing of the various circuit, as well as testing whether the circuits and chips are functional.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a pre-production, prototype multichip module which is adapted for performance timing and functional tests of production modules.
It is another object of the present invention to provide a process for producing such a pre-production prototype module which does not distort timing so as to prevent use of the module for preliminary performance testing.
A further object of the invention is to provide a method for determining the impact of the test circuits in a preproduction prototype board which minimizes impact to timing as compared to the production board.